Occupational noise exposure and risk of myocardial infarction: results from a prospective Swedish cohort.

OBJECTIVES

To explore the association between occupational noise exposure the preceding year and myocardial infarction (MI) and cumulatively.

METHODS

Data came from the Swedish National Cohort on Work and Health, a cohort of all Swedish individuals born between 1930 and 1990. We included individuals with at least one occupational code between 1985 and 2013, which was matched to a job-exposure matrix for occupational noise in five categories (LAeq8h): <70, 70-74, 75-79, 80-84, ≥85 dB(A). First-time MI was ascertained from national patient registers. We used a discrete-time hazards model to account for time-varying covariates and adjusted for individual confounders and other occupational exposures. We estimated the ORs for noise exposure in the year prior and cumulatively. Sensitivity analyses were done stratifying by sex and restricting to low physical workload.

RESULTS

Of 6 680 523 individuals, 75 437 were first MI cases. Compared with <70 dB(A), occupational noise was associated with increased odds of MI across all categories, with 1.13 (1.11-1.15) for 70-74, 1.13 (1.10-1.15) for 75-79, 1.13 (1.10-1.16) for 80-84 and 1.08 (1.04-1.12) for ≥85 dB(A). Associations were similar in restricted analyses to low physical workload and for men; among women, odds were increased at 70-74 and ≥85 dB(A). Cumulative exposure of more than 1 year to ≥85 dB(A) was also associated with increased odds of MI.

CONCLUSIONS

Occupational noise was associated with modestly elevated odds of MI, with consistent associations for exposure to over 85 dB(A) after taking into account other occupational factors.